This is intended as an information resource for those making the most of old computers, or choosing a new computer and software for the lowest possible cost. The needs of developing world users (language, maintenance, power, dust) in particular are considered, but the guide may be useful to people anywhere.

Remember that there is generally more than one acceptable solution; more controversial statements or disagreements may be best placed on the talk page. The ultimate aim is not to advocate particular hardware or software, but rather to meet the needs of people with limited resources, limited or no access to technical support, and/or limited education.

This is meant as a resource for those wishing to build low cost computers, suitable for developing countries, and for those wanting to reuse old computers or computer parts. The hardware choices are more relevant to new computers (or new parts) but the software choices apply to both.

It describes the choices available, depending on desired features such as:

ultra-low power consumption and battery or crank power (always desirable, but not essential if mains supply is available)

There are several projects to develop and sell a low cost computer for the developing world. These are not yet ready, although the XO-1 (laptop)W is planned for release in early 2008.

For more information, see the Wikipedia articles for these projects:

The XO-1 (laptop)W - formerly known as the $100 Laptop or Children's Machine, and being developed by the One Laptop per Child (OLPC) trade association.

This will be subsidized, and the $100 target won't be reached immediately. It was proposed that anyone can buy one, for approximately $300, which would help subsidize the cheaper ones. This proposal was canceled in Nov. 2006, see the OLPC Retail page for details. From November 2007 to the end of the same year the OLPC project had a "Give One, Get One" program in the USA for $399.

Has received some critical reports, but reports of its demise are exaggerated. Hasn't taken over the world, but it's serving a good number of children.

It has been criticized on various grounds, including by the Fonly Institute for being too restricted in distribution to only children, and being open to serious misuse - see the Wikipedia article for more.

This will be sold to Ministries of Education in multi-million units, and the $100 target won't be reached immediately. There have been discussions of a commercial version; however OLPC have said this is unlikely to happen for some time, though deliveries for groups outside formal education sector, such as refugee camps, might be considered.

African project (name, link?) more features and designed to be very sturdy and dust-resistant, but an estimated cost above US$1100. Intended for groups rather than individuals.

The simplified Inveneo computer (a computer for rural areas) designed in San Francisco by Inveneo, costs from about US$300(sh530,000) to US$470, is small, runs from a 12VDC battery, and uses a fraction of the power of a regular computer (18W maximum with LCD display).

The Raspberry Pi is a credit-card-sized computer which plugs into a monitor or TV, due for release in late November 2011. It is expected to have very low power consumption (minimum 1W, can be powered on 4xAA batteries), supports component or HDMI-out for display, 1 or 2 USB2 ports, SD-card slot for system, stereo-out, Ethernet (model B), 700mHz ARM processor with dedicated GPU, 128/256mb RAM. Price: $25 for Model A, $35 for Model B. Website. News report: The $25 PC is nearly here....

The WorldReader project, which is using the Kindle with African schoolchildren during its testing/demonstration phase (though their plan seems to be to get something cheaper with the same basic function as an e-reader).please expand

Since some years computers have enough resources to be used by more than one user ( even using a graphical interface ). What is needed is one or more graphic cards supporting more than one monitor and some USB keyboards and mice.

The main focus of this page (so far) is on desktop systems, and on reusing old computers, whether desktop or laptop. In terms of portable solutions, it will probably be hard to compete with the XO-1 (laptop)W.

However, feel free to contribute information on portability, in the appropriate sections.

While less than ideal from an environmental point of view (particularly where recycling options are not available), battery storage adds considerably to a computer's utility when used outdoors or with intermittent sources of power. Since batteries are also expensive, a computer with low power consumption is probably preferable to having more battery capacity. Many battery types also lose capacity over time, a process that can be accelerated by certain patterns of charging and discharging depending on the battery type.

One problem in locating new or used replacement batteries for laptops and similar devices is that most manufacturers will use a custom/proprietary form factor that prevents cross-compatibility with other brands and model lines. Norhtec's low-cost Gecko laptop uses eight standard AA sized rechargeable cells instead, eliminating the need to find a battery specifically designed for the device. Because of the broader market for standard battery types, prices can likely be more competitive.

To restore battery functionality to a laptop with a dead battery that has a non-standard form factor, it's possible to construct an external battery by wiring enough individual cells in series to create the voltage needed, and connecting that to the computer's DC input. With AA batteries this can be done with very inexpensive parts, but charging the cells in place would require additional circuitry. Power input jacks are much more likely to be of a standard type than the battery of the laptop, increasing the odds they will be available locally and inexpensively. Another method of restoring function would be to disassemble the original battery and replace the dead internal cells with functioning ones of the same number and type. This may be preferable if charging during operation is required.

Options

Cost

Power output

Operating time

Local energy production methods can be intermittent, which presents restrictions on usability if no power storage at all is in place. (#Crank power) is not unpredictable in the same way that {[solar power|solar]] or wind) power can be, but without any form of power storage the computer would turn off the instant you stopped cranking. Needing to generate power constantly to prevent immediate shutdown would make it considerably more difficult to use a hand-cranked computer since the hands are also needed for other tasks, but with foot/pedal power this would not be as much of an issue.

-- However, having the use of a computer only "sometimes" may still be an improvement over the having the use of a computer "never". -- In many places even mains power is not available 24/7, and people still prefer that over no mains power.Additionally, in some applications battery back-up can be made to palliate the inconvenience of intermittent power. (A pretty standard solar- or wind-recharged system, which have been made with technologies as primitive as recycled car batteries for decades now.)

The CPU is a major factor in a computer's speed, power consumption and software compatibility.
The clock rate W of a processor in MHz or GHz gives only a very rough idea of its capabilities unless comparing similar models, so it may be better to rely on real world tests to determine whether the system can perform a given task adequately. In some cases, processor intensive tasks (e.g. video decoding) can be offloaded to other components of the computer, allowing unbroken playback when otherwise the CPU alone might be unable to keep up.

Generally, recently made processors often have better power efficiency than older models, due both to miniaturization of components and active power saving measures not present in earlier chips.
Used systems can have a low initial cost, but a power-hungry used model may present a false economy, depending on the cost of electricity and the amount of time it will be in use. Over time this will be less of a problem as inexpensive power-efficient models reach the used market at progressively lower prices.

Processors based on the X86 W architecture are found in most personal computers that exist now, which generally means broad compatibility with available operating systems and other software. Current X86 processor model lines with low power consumption include AMD's GeodeW and VIA's C7W, both seen in different revisions of the OLPC-XO, and Intel's Atom W line which is found in many consumer netbooks.

ARM W based processors are another low-powered option if X86 compatibility is not considered essential. Processors of this family are frequently seen in phones and other handheld devices, but inexpensive laptops with processors and tablet computers with ARM processors also exist. Power consumption can be significantly lower than comparable X86 chips, but running most commercial software designed for X86 systems (e.g. a full Windows OS) is not ordinarily possible. This is less of an issue with open source software and operating systems, because an ARM version can be compiled by someone from the source code and redistributed.

Is a Geode (processor)W suitable? Low power, used in Embedded systemW.

Prices of CD and DVD drives and recordable media have declined to the point where there is no longer much of a price advantage to the older CD format either per disc or per drive. DVD drives are backwards compatible with the CD format, and DVD-RW drives also retain CD-RW write capabilities. In both cases, rewritable discs are more expensive than ordinary recordable discs that can only be written once, making them best suited to applications where the contents are only needed temporarily (e.g. testing). Since DVD discs hold many times more data than CDs but don't cost significantly more, the primary advantage of CD-R media today is playback on devices like audio CD players. Some audio CD players, particularly older models, are not able to play CD-R media though.

DVD drives and media come in a confusing array of varieties. Most notably, some drives will record to DVD-R but not DVD+R discs or vice versa, and some are unable to write to higher capacity dual layer media. Conversion of other video file formats to DVD can require a lot of time on a computer that's not moderately recent, and importing video from a source like VHS requires special hardware. DVD-RAM is a specialized disc format not compatible with stand alone DVD players.

Blu-ray has emerged as a successor to the DVD format, except in China where a variant of the competing HD-DVD disc format is still in use. Disc capacities are many times those of DVD media. As of 2011 there are significant premiums on Blu-ray drives and recordable media compared to DVD, but these have gradually diminished over time.

Cathode Ray TubeW monitors will most often be cheaper and more accesible than LCDW monitors. Be warned, however, of the risks in accepting free CRTs. You may end up with a dead monitor and a recycling fee.

Distributions of Linux typically include a range of applications. "Chubby Puppy Linux" includes more highly functional programs than most "MiniLinux" distributions, including OpenOffice, though it is slightly bigger at 96 MB. Additional suitable software may be found by following these links:

PortableApps.com - compact programs designed to run from a portable media such as a USB flash drive; they can also be installed on a hard drive.

By using Linux, we encourage and tap into a community of users and open-source programmers who are likely to support our efforts.

Windows also is more resource-hungry, less reliable and stable than Linux.

Windows XP is not supported by Microsoft any more (as of April 2014).

Windows 7 and 8 require 2 GB (= 2000 MB) of RAM and modern processors for useful
operation. Therefore, these Windows versions are no alternative for older computers
with 256 MB of RAM to 2 GB of RAM. To continue using those computers instead of having
them become electronic waste, an efficient Linux distribution like Lubuntu Linux (from
256 MB of RAM) is a good replacement for Windows XP.

Windows 98/ME (not supported by Microsoft any more) seems to be able to run Open Source applications faster than Linux on old hardware. Was also able to get more large Open Source applications to run on a Windows ME machine than on a Linux machine with a distribution geared to older systems (on the same computer).[Suggested project] My source for this was my own experience. I used a laptop running Windows ME and later on the same one running Linux, ran the same Open Source applications and saw a speed difference. I've also seen this mentioned on a few Linux blogs by users who run both operating systems. -- comment by anonymous contributor. With that in mind, ReactOS might be a good future solution (but is currently alpha, not suitable for everyday use . ReactOS is an Open Source operating system attempting to be compatible with Windows NT (and future versions) and to give compatibility with Windows native drivers, while using much less system resources.

Using a lightweight version of Linux specially designed for older computers may be the best option. Even 486 machines can run with some of these, although without a modern browser with flash etc. There is a wide choice of Linux flavors, called "distributions", which can be confusing to the newbie.

For a programming editor, SciTE is excellent. It can do many of the things a word processor can do plus anything a text editor can do.

Adobe AcrobatW, FoxitW, or other program to read (and perhaps write) PDF files.

There are several open source Linux pdf readers. Evince is quite a good one.

Writing PDF files can be achieved with OpenOffice, LibreOffice, and other word processors.

XPDF is available on some Linux distributions and I've read Sumatra (also available at Portableapps.com) for Windows users is based on it. There's also a Windows version of XPDF available at the GnuWin32 project at Sourceforge.